Abstract 124TiP
Background
Synchronous multiple primary colorectal cancer (sMPCC) is a clinically rare entity, but its incidence has been on the rise in recent years. Our previous research revealed a significantly higher incidence of deficient mismatch repair/microsatellite instability-high (dMMR/MSI-H) in patients with sMPCC compared to those with single primary colorectal cancer (SPCRC). PD-1 monoclonal antibody therapy has demonstrated remarkable efficacy in dMMR/MSI-H SPCRC patients. However, the safety and efficacy of neoadjuvant immunotherapy in patients with locally advanced dMMR/MSI-H sMPCC remain uncertain.
Trial design
This open-label, multicenter, single-arm, prospective phase II study conducted in China aims to assess the safety and efficacy of neoadjuvant immunotherapy in patients with locally advanced dMMR/MSI-H sMPCC. Patients are categorized into three sub-types: type 1, with both dMMR/MSI-H and proficient mismatch repair/microsatellite stable (pMMR/MSS) lesions; type 2, with all lesions exhibiting dMMR/MSI-H; and type 3, with all lesions showing pMMR/MSS. Enrolled patients include those with type 1 and type 2. Patients with mixed MMR status receive neoadjuvant combination therapy comprising mFOLFOX6 and PD-1 monoclonal antibody every 2 weeks for 6 cycles, while patients with dMMR/MSI-H receive neoadjuvant immunotherapy with PD-1 monoclonal antibody in the same cycles. This study represents the first prospective investigation into the safety and efficacy of neoadjuvant immunotherapy in patients with locally advanced dMMR/MSI-H sMPCC. The findings of this study are anticipated to inform personalized treatment strategies for sMPCC patients. Key inclusion criteria encompass histological confirmation of sMPCC, immunohistochemical or next-generation sequencing identification of dMMR/MSI-H, and clinical staging (cT3-4NxM0). Main exclusion criteria include stage IV, other malignant tumors within 5 years, long-term exposure to immunosuppressive agents, and refusal to provide informed consent. A total of 17 patients are planned for enrollment.
Clinical trial identification
NCT06002789.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.